1. Field of the Invention
This invention relates to the enhancement of combustion efficiency in an internal combustion engine by charging a mini-combustion chamber with a combustible fuel-air mixture during the compression stroke, by issuing a hot gas jet from a mini-combustion chamber into the main combustion chamber during the combustion stroke and then clearing or purging the mini-combustion chamber of burned gases by providing a closable passage for drawing ambient air through the mini-combustion chamber during the intake stroke.
2. Description of the Prior Art
Various efforts have been made over the years to improve the ignition process in internal combustion engines by providing mini-combustion chambers communicating with the spark gap region of a spark plug from which ignition propagates into the main combustion chamber. The purpose of such mini-combustion chambers is to provide a jet of hot gases which propagates into the main combustion chamber at a higher velocity than the propagation velocity of the flame front from the spark plug. The higher the jet propagation velocity, the more complete the combustion in the main combustion chamber. Such prior efforts have been directed to an overall design of the spark plug itself or to adapters which include a mini-combustion chamber in communication with the main combustion chamber. However, no provision has been made for purging or flushing the burned gases from the mini-combustion chamber with ambient air.
For example, U.S. Pat. No. 1,359,591 to Grimes is directed to a spark plug having a hollow shell which forms a firing chamber. When the spark plug discharges or sparks, the fuel-air mixture contained in the hollow shell firing chamber is ignited and expelled as a jet through a restricted passage into the combustion chamber of the engine cylinder to effect ignition of the fuel charge in the cylinder. The shell is described as being frustoconical and having the restricted passage located at the cone apex. The hollow shell firing chamber may be formed integrally with the spark plug or may be provided as a threaded adapter to which a conventional spark plug is engaged. The adapter is threaded to engage a spark plug port of an internal combustion engine. This patent does not provide for purging by ambient air of burned gases contained in the firing chamber.
U.S. Pat. No. 1,522,551 to Shepherd is directed to an adapter threaded to receive a spark plug and also threaded to engage a spark plug port of an internal combustion engine. The adapter is formed to provide an ignition chamber in the region of the spark plug gap. A Venturi-shaped throat provides a passage which communicates with the cylinder combustion chamber. The Venturi throat, in the region diverging in the direction away from the ignition chamber, is roughened or corrugated so as to prevent oil or other contaminants from entering the ignition chamber. In the region converging in the direction away from the ignition chamber, the Venturi throat is smooth. The Venturi throat can be made of porous materials which absorb oils. The function of this Venturi throat is not directed to enhancing jet flow velocity since the roughened walls tend to decelerate the flow. In one embodiment, the electrodes forming the spark gap are extended such that the spark gap is located downstream of the Venturi outlet. The extended portions of the electrodes act as spoilers and hinder penetration of the jet into the main combustion chamber. In addition, this patent does not provide for means to purge with ambient air burned gases from the ignition chamber.
U.S. Pat. No. 4,182,281 to Heintzelman is directed to a spark plug adapter having a preliminary combustion chamber divided into a wider upper portion and a narrower lower portion. The preliminary combustion chamber has a restricted opening for communicating with the cylinder combustion chamber. The restricted opening has a knife edge therein and can either be diverging in the direction away from the preliminary combustion chamber or converging-diverging in the direction away from the preliminary combustion chamber. A helically-shaped insert having a cross member and located within the lower portion of the preliminary combustion chamber promotes turbulence of the jet expelled from the preliminary combustion chamber through the restricted opening. The insert has no opening because the flow is subsonic, allowing any disturbance to wash out at the speed of sound. In addition, this patent does not contemplate the purging of burned gases from the preliminary combustion chamber.
U.S. Pat. No. 4,499,399 to Flores is directed to a spark plug adapter provided with an upper preliminary chamber in the region of the spark gap connected by an acceleration orifice to a lower chamber. A deflector is disposed beneath the exit of the lower chamber so as to promote turbulence in the exiting ignited fuel mixture. The upper chamber is shown to converge toward the acceleration orifice. External fins are provided to cool the upper chamber. Because of the apparent ratio of the length to diameter, the acceleration orifice and the lower chamber function only to slow the flow velocity and increase heat loss from the jet. The deflection element further impedes the resulting jet velocity. This design also fails to purge burned gases from the preliminary combustion chamber with ambient air.
U.S. Pat. No. 3,710,764 to Jozlin is directed to an integral spark plug or a spark plug adapter having an ignition chamber communicating with an exit port. A one-way valve is disposed between the ignition chamber and exit port. One or more relatively small jet passages are provided to permit expulsion of a jet of burning gas through the port into the engine combustion chamber. Various valve and jet passage arrangements are disclosed. The purpose of the valve is to permit buildup of pressure during ignition in the ignition chamber surrounding the spark gap. However, because these passages are small in diameter and have a large aspect ratio of length to diameter, they slow the flow to low speed. In addition, these passages tend to cool the jet gases, and no means are provided to purge burned gases from the ignition chamber.
In view of the foregoing limitations and shortcomings of the prior art devices, as well as other disadvantages not specifically mentioned above, it should be apparent that there still exists a need in the art for a device for issuing a high velocity jet into a combustion chamber. In addition, there is no provision made in the Patents discussed above for purging the mini-combustion chamber of burned gases with ambient air.